Painting window frames is a tedious and time-consuming task as the painter desires to fully cover the window frame while avoiding getting the paint on the window pane itself. Often, windowpane glass is separated by narrow dividers known as mullions. The mullion is a slender member placed between adjacent panes of glass supported by a flange and held in place by putty, caulk or a narrow strip of wood that covers the outside edge of the glass adjacent the mullion. When the window frame or mullions are painted, the paint which otherwise gets on the window pane must be thoroughly removed.
Past efforts at keeping paint from getting onto the windowpanes had been accomplished by masking the glass with tape along the perimeter of the pane where glass meets frame or mullion. When masking, an adhesive coating or tape is placed on the windowpane so that the trim or frame material can be painted quickly and without regard to the juncture between glass and trim since any excess paint will be applied to the protective coating. However, taping is laborious and time consuming and removing the tape from the glass often presents problems, particularly where the tape hardens or becomes tacky. Where tape has not been employed, paint must be scraped off the glass, typically with a razor blade. Another method of masking involves a triangular mask with an adhesive strip around the perimeter. The triangular mask is applied to the glass surface and overlapped to cover the entire surface with a portion of the mask. Portions that overlay the mullions would need to be cut off so as not to interfere with the painting of the frames. Another device provides a flexible narrow blade with a straight edge that contacts the mullion. The ends of the blade are cut at an oblique angle. Two adjacent blades join at a corner of the window. A rubber vacuum cup attaches to each of the blades for securing the blade to the glass. Another device has a spring clip which engages opposed mullions frictionally. The clip presses a cardboard paint shield firmly against the adjacent windowpane. Another device involves a fitting that permits the application of caulk along the perimeter of the pane which may be peeled off subsequent to painting. Yet another window mask product consists of a razor blade mounted on a squeeze bottle containing a liquid paint mask composed of petroleum distillates, which mask is applied to the window's perimeter through a sponge applicator pad and left to dry. After the mullions and frame are painted the paint and mask drippings are scraped off with the attached razor blade.
Each of the foregoing paint mask efforts is plagued with drawbacks. The triangular shield designed to fit over the glass must be cut to size and the overlaps of triangular sections leave gaps that allow paint to seep onto the glass. The blade-style shield alluded to are labor intensive and require accurate positioning of adjacent shields to protect the glass surface. The cardboard shield becomes damp with paint and losses its effectiveness to seal the glass from painting. A spring clamp must be inserted to hold the cardboard sheet to the window. The caulk applicator requires the costly purchase of caulk, the manipulation of a relatively cumbersome caulk applicator, caulk build-up within the applicator, and time-consuming cleanup following caulk application. The razor blade/squeeze bottle method suffers the disadvantage of dripping, it requires time to dry onto the protected surface prior to painting, its petroleum distillate composition is an irritant to skin and eyes, and the use of a razor blade to remove paint scratches treated and energy efficient glass.
Commercial efforts at paint masking include the use of masking tape, caulk, masking paper and liquid paint masks. The liquid paint masks are applied by spraying, sponging, brushing or rolling. Hand-held portable paint mask applicators include a hand-held masking machine which applies masking paper to a desired location, and a fitted nozzle for a caulk gun that permits a bead of caulk to be applied along a window pane's edge and later peeled away. Accordingly, there is a need in the art for an improved mask for glass to prevent painting the glass while painting mullions.